What is the "fill power" of feathers?

In catalog data and advertising complaints of climbing supplies such as sleeping bag and down jacket,Fill Power (FP)I think that often look at the numbers.

As a measure of the quality of feathers, feathers used for climbing equipment etc."XNUM X Fill Power"More good quality down is used.

Well then, what kind of unit is this "fill power"?

In a word, the original definition is

"How many cubic inches of weight X NUM X ounces of feathers will expand"

It is a number.

FP = in3 / oz

For example, 600 fill power means that 1 ounces (28.35g) feathers swell to a volume of 600 cubic inches (about 9832cm3).

In this way, the swelling of the feathers (height of the cushion) is quantified and expressed.

Therefore,The larger this number, the lighter and the better it can be said that it is a measure of good feathers that swell well.

Testing cylinder for IDFL (International Down and Feather Testing Laboratory)
(From the Isca WEB site)

There are various methods for this measurement, but in the originally used USA method, 9.75 ounces of feathers are inserted in a cylinder cylinder of inner diameter 1 inches, a disk of weight 68.5g is placed on the bulging state, and sunk It was defined as how many cubic inches the volume was when the height was settled.

At present, according to the IDFB method (International Feather Association Method), which is regarded as the world standard, the volume of a cylinder with an inner diameter of 288 mm is obtained by placing XNUM g of feathers and loading with an XNUM X disc.

Of course, because the flow of old numbers, the volume isCubic inch notation.

In Japan's JIS standards, the height is about 0.3 mm when measured with a slightly heavy disk with the same tool stand as this."High bulk"It was expressed as

However, it is probably because "fill power" has become popular recently, in the metric method, the volume under load of XNUMxg, which is the same as that of FP in JIS, is expressed in cubic centimeters per feather XNUMxg."Down power" (dp: cm3 / g)It came to be written in.

By the way, the load of XNUM Xg is generally assumed that feathers packed in a futon always receive about X NUM X kg / m X NUM X (approximately X NUM X Pascal) pressure, and with an equivalent force It is because it imitates the squeezed state.

Attach to luxury feather futon etc"Gold label" Of"Excel"And"premium"It is based on this standard.

For example, "premium down" of the finest duvet is considered to be more than down power 440, but to convert it to fill power, it is sufficient to express the volume of X NUM X g in cubic inches.

Volume: 440 (cm3) x 30 (g) = 13200 (cm3)

Since 1 cubic inches is about 16.38cm3, 13200 ÷ 16.38 = 805, which means 805 fill power.

As well
Down power more than 400"Royal down"It is,
About XNUM X Fill Power

Down power more than 350"Excel down"It is,
About XNUM X Fill Power


After all the luxury duvet is using a good down.

Among the best down-selling products for mountain climbing, there is, for example, the Montbell EX Down (XNUM X Fill Power).

If this is converted to JIS down power, which is an easy-to-understand metric, it will be approximately 546.

In other words, this down means that only XNUMxg will expand to the volume more than XNUMx bottles.

Of course, whether it's wear or scraping, the performance of feather products can not be expressed with fill power alone.

For example, in the case of a sleeping bag packed with XNUMxg, the highest grade of 800FP and a sleeping bag packed with XNUMxg down, the latter is warmer.

How to compare cold insulation
You don't know unless you look at the "volume" of the contents.

Also, no matter how high-quality down is used, FP is only a guide because the performance of the product, including the fabric, sewing, design and cutting when it is made into a product, is integrated.

Bunichi Kaneko
Configuration PORTALFIELD editorial department

Leave a comment

What's your evaluation?

avatar image

Distributor Keiichi Kaneko

Recommended for students! Gore-Tex Rain Suit (Men) Pro Monte SR135M

"We walk the lower corridor, the old Nichido sidewalk, horizontal footpath" again